This is verbatim from the folks who developed these services -
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You can look at the messages via the MSMQ admin console with the following steps:
start compmgmt.msc
go to Services And Applications - Message Queueing - Private Queues - avdirchangequeue{guid} - Queue messages
Right click on one of the messages and choose properties
You'll be able to see the binary contents of the message. However, it is difficult to interpret without knowing the binary structures that are being serialized (and even then it is time consuming to reassemble them by hand).
A more civilized way to look at the messages is to turn on the "All Change Requests" diag of the Directory Change Writer. It prints a pseudo-readable version of each change request as it applies it to the SQL database.